In this research project, we will examine the proposal that different segments of the pulmonary vasculature have different characteristics in response to autonomic drugs. Specifically, we will determine a) the distribution of sensitivity of the smooth muscle contracting and relaxing effects of alpha and beta adrenergic agonists, b) the distribution of sensitivity to stimulation of adrenergic neurons compared to the response to exogenously applied norepinephrine and tyramine, c) the distribution of sensitivity to inhibition of neurogenic norepinephrine release by alpha adrenergic and muscarinic receptor agonists, d) the distribution of sensitivity of the smooth muscle to effects of specific antigen in tissue taken from sensitized animals and the inhibition of antigen-induced effects by beta receptor agonists, e) the effects of chronic alveolar hypoxia and hyperoxia on responses in the above-mentioned studies and f) if differing sensitivities between segments or changes in sensitivities by oxygen are a result of changes in receptor characteristics.